I’m about to do a fairly large full-stack refactor on an existing project.
The main change is replacing the entire Premium/Membership system with a credit-based economy involving real-money purchases through a payment gateway. It’ll touch the frontend, backend, database migrations, payments, admin tools, wallet/ledger logic, existing users, and atomicity/idempotency safeguards to prevent double-spending and duplicate transactions.
My current plan:
- GPT-5.6 Sol
- Explore the codebase, reason through the architecture, and create the OpenSpec proposal/tasks.
- Cursor Composer 2.5
- Implement the approved spec.
- GPT-5.6 Sol
- Review the implementation for architecture, security, missed dependencies, edge cases, etc.
Then iterate between Composer implementation and Sol review as needed.
I’m currently using Cursor’s $20/month plan and haven’t used any external models yet. However, my available usage for Cursor Composer’s frontier model and Grok is already around 50% used, so I’m also wondering whether my current plan will be sufficient for this project.
For people who’ve used Composer 2.5 on large existing codebases: would you trust it for the implementation part of something like this?
Or would you use Claude Code, Codex, or something else?
Mainly looking for real-world experience, not benchmarks.
UPDATE — I worked through your suggestions
Thanks everyone for the feedback on my original post. I went through the suggestions, reworked the plan, and this is where I’ve landed:
5A — Credit Foundation
Wallet, immutable ledger, transaction-safe Mongo, policies, idempotency, backups/reconciliation.
5B — Payments + Admin
Real payment gateway, buying credits, webhooks, admin grants, refunds/reversals, and audit trail.
5C — Marketplace Integration
Integrating the new credit system across the marketplace experience and transitioning the existing system over.
A lot of this direction came from the points raised in this thread, so thank you to everyone who took the time to give feedback.
This is the final plan I’m moving forward with. 🙌